Direct-methane solid oxide fuel cells with hierarchically porous Ni-based anode deposited with nanocatalyst layer

Abstract

Current development of solid oxide fuel cells (SOFCs) is impeded by direct utilization of hydrocarbon fuels since SOFC anodes suffer from coking readily. We present an innovative design for enhancing the coking resistance of the conventional SOFC anode. A thin nano samaria doped ceria (SDC) catalyst layer has been deposited efficiently via infiltration on the wall surface of the Ni-yttria-stabilized zirconia (Ni-YSZ) anode internal gas diffusion channel (5-200 μm in size) fabricated from freeze-drying tapecasting and vacuum-free infiltration. The efficiency for catalyst infiltration has been significantly improved by using hierarchically porous anode structure with open and straight channels. Single cells with nano SDC layer show very stable cell performance and a peak power density of 0.65 Wcm-2 at 800 o C using methane as fuel. High resolution transmission electron microscopy (HRTEM) analysis indicates for the first time that SDC layer can effectively prevent the formation or growth of nickel carbide (onset of coking), accounting for the excellent performance and structural stability of the Ni-based cermet anode.

Stability Investigation for Symmetric Solid Oxide Fuel Cell with La0.4Sr0.6Co0.2Fe0.7Nb0.1O3-δElectrode

“…The cell showed reasonable stability using H 2 and methane as the fuel and no significant power output degradation was observed for 70 h operation. The precipitation of alloy can preferentially oxidize carbon species or fragments, removing them from the surface of the electrocatalyst rather than forming carbon-carbon bonds or nickel carbide, [31][32][33][34] suggesting that LSCFN is a promising anode material with coking resistance. The redox cycling stability of the LSCFN electrode was demonstrated in Fig.…”

A Highly Efficient Sandwich‐Like Symmetrical Dual‐Phase Oxygen‐Transporting Membrane Reactor for Hydrogen Production by Water Splitting

“…However,c heap Ni-based catalysts are prone to deactivation as ar esult of coke deposition (that is,c arbon buildup) once pure methane has been used as the feedstock, similar to the effect observed in industrial processes for methane reforming. [6] Although great efforts have been focused on the development of coke-resistant catalysts, [7] coke-deposition-induced performance degradation is still difficult to avoid. To maximize the function of the OTM, it is crucial to balance the high chemical stability and the practical oxygen permeability.W henc obalt/copper-containing perovskite oxides (for example,Ba 0.5 Sr 0.5 Co 0.8 Fe 0.2 O 3-d )are employed as membrane materials,t he performance of the reactor may gradually degrade with time because of the easily reducible active cations.…”

“…[4] Relatively recently,a no xygen-transporting membrane (OTM) reactor, consisting of mixed ionic and electronic conducting (MIEC) materials,was applied to the water splitting reaction. [6] Although great efforts have been focused on the development of coke-resistant catalysts, [7] coke-deposition-induced performance degradation is still difficult to avoid. To ensure rapid removal of oxygen, methane/biomethane was fed on the sweep side of the membrane to consume the permeated oxygen by partial oxidation of methane (POM) to syngas.…”

“…[10] Thus,a nM IEC-IC composite dualphase membrane is believed to be aprospective candidate for application in chemical reactors ( Figure 1). We also foresaw that coking could probably accompany the syngas production, [6,7] which deactivates the catalyst and leads to ad ecrease of the hydrogen production rate from water. [12] Herein, we present adual-phase OTM reactor with asandwich-like symmetrical configuration, whereby two porous backbones built up on both side of the dense functional layer may alleviate the performance losses caused by slow surface-reaction kinetics ( Figure 1a).…”

Geometric Modeling of Infiltrated Solid Oxide Fuel Cell Electrodes with Directional Backbones

“…The efficiency for catalyst infiltration has been significantly improved, by using hierarchically porous anode structure with open and straight channels. This structure significantly inhibited the coking growth by preventing the formation of nickel carbide, where the excellent performance and structural stability of the Ni‐based cermet anode were guaranteed . Torabi et al investigated the impact of porous support morphology on the electrochemical performance of LSM‐infiltrated symmetrical cells.…”